The reservoir was built by a consortium of Penicuik mill owners in 1850 to help regulate the flow of water in the river to give a constant supply to the numerous paper mills which had sprung up in the valley. The engineer responsible was Thomas Stevenson, father of Robert Louis Stevenson.
This is a lovely walk, full of variety and contrast. In the beginning it is in a beautiful secluded Glen and then opens out cross a grassy hillside with magnificent views along the Pentland ridge.
Take some time to enjoy the view over the reservoir. The islands in the reservoir is home to many migrating birds during the summer months. So be sure to take your binoculars with you.